distant botanical   relatives   share   elements    of
its biochemistry    and therefore   its flavor; these
include capers  and papayas (pp.    409,    381).
The  Flavor  Chemistry   of  the     Cabbage
Family   Like    onions,     cabbages    and     their
relatives    stockpile   two     kinds   of  defensive
chemicals    in  their   tissues:    flavor  precursors,
and  enzymes     that    act     on  the     precursors  to
liberate    the reactive    flavors.    When    the plant’s
cells    are     damaged,    the     two     stockpiles  are
mixed,   and     the     enzymes     start   a   chain   of
reactions    that    generates   bitter,     pungent,    and
strong-smelling  compounds.  The     special
cabbage-family  system  is  effective   enough  to
have    inspired    a   notorious   man-made    version,
the  mustard     gas     of  World   War     I.  And     the
cabbage family  turns   out to  have    parts   of  the
onion   defensive   system  (p. 310)    as  well;   these
contribute   some    sulfur  aromatics   to  the
overall family  flavor.
The stockpiled  defensive   precursors  in  the